QuestionCheers Garry,I'm afraid i've just realised that i didn't quite explain the problem correctly.. The Fan is running ALL the time.. but at low speed.. It is when the amp heats up and switches from low to high the crack happens, and when things go quiet again from high speed to low causes another crack. Does this mean that that capacitor theory would not work as it would already be fully charged by the time the amp switches from high to low.etc. Maybey i should look at another theory like a relay causing the problem or something. or to get the fan running at full speed all the time so there is no need to switch up or down.?
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Cheers Garry, Thanks for the reply. That's really made my day. Looks like I did learn something at college then. Can I ask just another quick one, do you think this capacitor in parallel across the power lines to the fan will in anyway alter the amps performance or effect anything else that it I should be concerned with and should i mount the capacitor (once i have tested them)on a little board in the amp or just solder it loose across fan terminals. Oh yeah, and should i use heatshrink on the capacitors legs.? Sorry thats three questions.
Cheers mate !!
Chris.
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Hi Garry, i've got a bad problem with my amp, and i was hoping you could help me out !
I've got a Peavey PV 500 power amplifier ( 2 * 250 watts) which i use to gig with in pubs and stuff. The things got a built in cooling fan which turns on when its used at high volumes and off when things go quiet ( ie in between songs ) The problem is that it gives out a 'Click' eack time it switches on or off and at high volumes it becomes a massive 'CRACK' thats gonna knacker my speakers if it goes on much longer. I used to have a set of Peavey speakers that were already knackered anyway so i was never too bothered about it until now as i have purchaced a new set of Soundlab speakers which are great and i really need to keep them that way. The crack now sounds ten times louder than it used too as the speakers are much better than the old lot.
I used to do electronics at college about ten years ago and i remember a theory of placing a Capacitor across a component to stop spiking occuring. Do you think this will work or have you got any other theories on how to solve this problem as i'm now afraid of using the speakers at high volumes, which means i cant take them out to gig with.
I would really appreciate your opinions on this as i really need to get out gigging again as i'm just about to go full time.
Cheers mate.
Chris
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yes, i'd try some non polarized caps across power lines to fan. i'd start with 1uf, then 10uf, then 47uf, up to 100 uf, whichever works best...
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it shouldn't make any difference in sound at all. i'd use a glob of silicone to mount it somewhere out of the way, but in close proximity to the motor. use heat shrink if you desire, just make sure the connections are soldered well.
Answerok, try this... replace the thermal switch, it should look like a large transistor with 2 wires attached, mounted on the heatsink for the outputs. once you unmount it, there should be some numbers on it, these should be it's closing temperature. just go to a heating and a/c supply (if you don't have an electronics parts dealer nearby) and they should be able to match it up with something. *note... replacement not need be exactly the same physically, just needs same closing temperature setting. ( fan runs through resistors to make low speed, thermal switch closes at set temp, and just bypasses resistors)....i'll still be here.....
